Nowadays, treatment for human health-threatening diseases such as diabetes, cardiovascular disease, respiratory disease, liver disease and cancer still progress slowly although medicine and related science continue to advance. The reasons why such diseases cannot be detected early include that on the one hand, early signs of these diseases are unobvious and protein factors uniquely secreted by disease cells are too few to be inspected by the conventional detecting means; on the other hand, even if the protein factors can be detected, it is both costly and time-consuming. Therefore, it is of profound significance to develop a highly sensitive, fast and low-cost disease sensor for human health-threatening disease treatment.
Generally, disease sensors used in industry are electrochemical sensors, optical sensors, FET sensors based on nanotechnology, or the combination thereof. The technology of electrochemical sensors is comparatively mature, but it places highly demands on solution condition and requires large volume. Moreover, to any kind of disease, the disease-related molecules are various and probably independent to each other, thus joint detection should be performed to the various disease-related factors for accurate disease detection. However, the conventional disease sensors can merely detect for a single target molecule. By contrast, FET sensors based on silicon nanowire (SiNW) array and utilizes field effect transistors to achieve signal collection and signal amplification can detect the target signals more effectively.
For example, the Chinese patent application no.CN200910030342.7 discloses a manufacturing and integrating method of a highly sensitive multi-channel bio-sensor. Compared with the conventional detectors, the FET sensor based on silicon nanowire array has the following advantages:
1). high sensitivity: firstly, the field-effect transistor itself has signal amplification function which can amplify small amount of charges applied thereon; secondly, the nanowire has large specific surface area and quantum confinement effect, which can increase the sensitivity of the FET sensor based on nanowire array;
2). fast detection speed: the detection speed of the FET sensor based on silicon nanowire array can reach GHz frequencies, which is much higher than that of the conventional sensors;
3). easy integration and high throughput detection: compared with the conventional sensors and detectors, the FET sensor based on silicon nanowire array has the advantages of easy integration and low cost; since the FET sensor can be manufactured by standard semiconductor fabrication process, the manufacturing process of the FET sensor is compatible with the semiconductor technology and the emerging MEMS technology, thereby achieving sensing with rich function and superior performance.
However, for structures based on silicon nanowire array, during the process of technology research and application, there still exists problems to be solved:
1). vulnerable to pollution in preservation and in use: since the silicon nanowire array has high surface sensitivity, merely forming a SiO2 passivation layer (as mentioned in CN200910030342.7) is hard to prevent the pollutants of Na ions and K ions or to block the effect of environmental factors such as PH value and humidity; accordingly, the sensor chip is greatly affected by the salt content, the PH value and the humidity of the environment and is difficult to be preserved or transported;
2). performance instability in use: in biological detection, due to the diversity of bulk and solution of the samples, the chip sensor may also be subjected to spread pollutants such as Na ions, K ions, Fe ions, Cu ions and Ca ions and effects of various chemical factors including the PH value. From the experimental and research results, the detection is shown unstable.